Abstract: The National Longitudinal Survey of Youth 1979 (NLSY79) is a nationally representative sample of men and women who were born in the years 1957 to 1964 and living in the United States when the survey began in 1979. The sample members were ages 14 to 22 during the first round of data collection. A primary focus of the NLSY79 is labor force behavior, but the content of the survey is considerably broader. The NLSY79 includes questions on educational attainment, training, income and assets, participation in government programs, health, workplace injuries, insurance coverage, alcohol and drug use, sexual activity, marital and fertility histories, and other topics. The NLSY79 was conducted annually from 1979 through 1994 and has been conducted biennially since 1994. The original sample included supplemental samples of blacks, Hispanics, economically disadvantaged nonblack/non-Hispanics, and youths in the military. The military supplemental sample was discontinued after the 1984 survey, and the economically disadvantaged nonblac/lnon-Hispanic supplemental sample was discontinued after the 1990 survey. The total sample now eligible for interview is 9,964 (including about 420 sample members reported as deceased in 2004). Of this total, 7,661 were interviewed during the 21st round of interviews in 2004. for a retention rate (adjusted for mortality) of 80.3 percent.